Corrosion checking device



Janl2, 1937 B. o. GoDFREY CORROSION CHECKING DEvVIC E Filed July 24, 1935 k2] Bert 0. Godfrey.

gru/umm Patented Jan. 12, 1937 UNITED STATES PATENT'oFFicE f COBBOSION CHECKING DEVICE Bert 0. Godfrey, Brooklyn, N. Y.

Application July 24, 1935, Serlal No. 32,933

The object of this invention is to prevent corrosion of boat parts such as propellers, propeller shafts, stuilng boxes, or'the like, which' are subject to corrosive electrolytic action, by 5 providing a metal body in metallic circuit or contact with one or more of said parts. A further object of this invention is to construct such metal body in the form of a sectional collar comprising a foundation of metal of substantially the -same polarity as that of the metal part to which the collar is' attached and anchoring the said electronegative metal to such foundation in a. manner that the collar will not become loose regardless. of the amount of corrosion action to which the Velectronegative 15 metallic part of the collar may become subwith the propeller shaft or other of said boat jected, parts. 'I'hese screws are of a metal having sub- With these and other objects in view, referstantially the same polarity in theelectromotive ence will be had to the accompanying drawing, series as the metal of the core sections 1. wherein: The adjacent faces of the ears 9 and I0 pref- 20 Fig. 1 is a view inside elevation illustrating erably do not tightly close together, but the a propeller, propeller shaft, stulng box and inner semi-circular faces I5 of the core secskeg of a boat, and with the collar comprising tions tightly engage opposite faces -of the prothe invention applied to the propeller shaft, peller shaft or like boat part throughput must,

Fig. 2 is a vertical sectional yview taken if not all, 0f their Meas- LikeWiSe, the adjacent 25 through the collar longitudinally of its axis, faces of the zinc shroud do not tightly close Fig. 3 is a vertical sectional view taken together, but their faces I6 like the core faces through the collar transversenf ef its axis, may, though net necessarily, bind upon 0p- Fig. 4 is top plan view of the core of the upper posite sides of the shaft or othenboat part. The section of the collar before the -same is enmetal of the shroud sections 8 is `counter-sunk 30 shrouded by the electronegative metal, at W a11d In fOr free Passage 0f the heads 0f Fig-5 is a view similar to Fig. 4 of a, modified the Iscrews or bolts II into direct binding enform, andv gagement with the core ears 9.

Fig. 6 is a. vertical sectional view of the core While satisfactory results may be obtained section of Fig. 4, in a degree by simply enveloping the sides and 35 Fig. 7 is a fragmentary vdetail of a modiflouter faces of the core sections in zinc cast cation.. f thereupon, a more positive anchoring means has In Fig. 1 of the drawing, reference nuineral been devised in the nature 0f uns or prejections 2 .designates the skeg or keel of a boat, 3 the 011th@ 0016 SeCtOIlS. With Which the metal 0f stuing box, 4 the propeller shaft,' Sthe pra. the shroud sections interlock, such interlocks- 40 peller, all of conventional form, and 6 the collar being unaffected by COITOSOD 0f the Zinc Shllld `which forms the subject matter of this inthrough a' 1011 Period 0f its lifevention. i These interlocks comprise parallel annular 'I'he preferred form of collar is illustrated in Series-0,1' integral` ears I9 formedintegrally With Figs. 2 to 4 inclusive, and said collar consists each c01@ SeCtiOIl 'l and the ears 0f One Series 45 of two sections, each composed of a core 'I embeing bent toward and partially into the Plane bedded in a .zinc shroud 3 The core 1 is com.. of the .ears of the other series and tting' beposed of a metal having a. position in the electween the latter ears. These ears may or may tromotive series approximating that of the part not be perforated as at 20 to Iafford additional to which the collar is to be attached to subinterlocks for the zinc which flows into' such stantially avoid electrolytic action between the perforations during the casting operation. This core and the said part. Were an all zinc splitl lateral bending of the. ears I9 offsets centrifcollar attached to a propeller shaft or other boat ugal throw of the zinc when the collar` is atpart, corrosion of the zinc would soon loosen tached to a rotating propeller shaft or propeller. 65

the collar so that the same would not .only rattle 2 claims. (ci. 11i-6 5) but would virtually lose its effectiveness for the intended purpose. By employing an attaching means of the nature described, these defects are avoided.

The zinc shroud 8 may be attached to the core I of each section in various ways to assure its attachment through a long period in the life of the zinc, but a very eiective mode of attach- Y ment is by casting the zinc 8 upon or around the core.

I0, and screws or bolts II pass freely through holes I2 in the ears 9 and screw into threaded openings I4 in the ears I0, clamping' the collar sections tightly uponr in non-rotative relation Each core section 1 is formed with ears 9 and The modied form illustrated in Figs. 5 and 6 is substantially the same structurally as the preferred form, except that parallel uninterrupted ribs are provided on the core sections and these are perforated at 22 to function like the perforations 2U in providing interlocks forvthe zinc shroud.

While zinc has been specified as constituting the metal of the shrouds 8, other metal standing' on the electronegative side of the electromotive series from the metal of the parts of the boat to be protected may be employed. The core sections 8 and screws H may be of metal standing substantially in the same position as thel metal of the part to be protected, and since such parts are usually of bronze, that metal isv generally the one used. Where bronze'propellers are used with steel shafts, zinc is used for the shroud 8 and a metal adopted for the core sections 8 from the electromotive series as will be best suited to insure longest life of th'e parts subject to corrosion.

The collar 6 is preferably clamped around the propeller shaft in metallic contact with the propellerA or stuffing box, according to which is to be protected, though satisfactory results are obtainable byxmounting the collar on the propeller shaft away from the propeller or stuffing box. Obviously the collar may be applied to any other boat part subject to corrosion through electrolytic action between sea-water and metals of different potentials inthe electromotive series.

While two forms of anchoring` means have been disclosed for securing the corrosive metal to the substantially non-corrosive core sections, it will be clear that the anchoring means is susceptible to many variations.

In practice the device has been found to be very effective for the designed purpose, and while a correct theory explaining its action may not be giyen, it is believed that the zinc or other metal selectedA from the negative end of the electromotive series, becomes the negative pole in an electrolytic circuit with the metals of the propeller, propeller shaft, and stuillng box, all of which are from the positive end of thel electromotive series, the sea water acting as the electrolyte. In such a circuit corrosion is confined principally, -if not entirely, to the most electronegative material, and is checked to a high degree in the other metallic parts.

Obviously7 the core parts 'l could be constructed of bakelite or similar non-metallic material since their purposeis to provide a. noncorrosive means for attaching the corrosive shroud 8 to the propeller shaft or other marine structure part, and the screws could be of the same non-metallic material, reinforced or not, or even of non-corrosive material relatively to the metal of the shroud. Metallic circuit is established between the corrosive shroud 8 and the propeller shaft or otherpart to which the collar is attached by 'a metallic plug or conductor 25 preferably of the same metal as the said propeller shaft or other part.

'I'he present invention makes it unnecessary to run any exposed wires between parts, particularly to get around any non-conductive material placed between the zinc or negative metal and the metal part to be protected.

What isclaimedr- 1. A collar for a propeller shaft comprising two semicircular sections each having diametrically opposite ears, means associated with the ears for tightly clamping the collar sections about said propeller shaft, said collar sections each having a radial extension having a wall portion disposed at an angle 'to the radius of the extension, and a metal negative in the electromotive series to the metal of the propeller shaft to be protected cast upon each collar section and enclosing the exposed outer surface thereof and its radial extension, said cast sections'being provided with an opening affording access to said clamping means,

2. A collar for a propellerl shaft comprising two semi-circular sections each composed of a relatively non-corrosive material, means associated with said collar sections for tightly clampingvthe collar sections about said propeller shaft, each of said collar sections having radial extensions along the outer edge thereof, said extensions being curved or arched inwardly from the outer edges of the collar section, their ends intermeshing, and a metal negative in the elec-A tromotive series to the metal of the propeller 'shaft to be protected cast upon the 'outer exposed surface of the collar section and enclosing -the said curved radial extensions, saidv cast section being provided with an opening affording access tosaid clamping means. 

